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D5556-19 – Standard Test Method Technical Guide
🎯 Scope and Significance
This test method covers the determination of moisture and other volatile material under conditions of the test. It is applicable to all fats, oils, and fatliquors used in the softening and stuffing of leather. The values stated in SI units are to be regarded as standard. This test method was developed in cooperation with the American Leather Chemists Association.
⚙️ Apparatus and Procedure
The required apparatus includes an electric hot plate with uniform heat transfer, glass beakers of 100 to 150 mL, and a desiccator with an efficient desiccant. The procedure involves accurately weighing 5 to 10 g of a well-mixed sample into a tared beaker. The sample is heated on the hot plate, slowly increasing to medium temperature settings, while rotating the beaker gently to avoid spattering. The approach of the end-point is judged by the cessation of rising steam bubbles and absence of foam. A clean, dry watch glass can be placed on the beaker to indicate steam evolution through condensation. The temperature should not exceed 130°C except at the end of the test, when the sample is heated momentarily to incipient smoking.
⚠️ Care must be taken to avoid spattering during heating. If spattering occurs, stop the experiment and use an alternative technique.
| 🔧 Equipment | 📏 Specification |
|---|---|
| Electric Hot Plate | Uniform heat transfer, chemical and scratch resistant |
| Glass Beakers | 100 to 150 mL capacity |
| Desiccator | Contains efficient desiccant |
📊 Calculation and Reporting
The moisture and volatile matter content is calculated as a percentage by weight using the following formula:
% Volatile matter = ((S + B) – D) / S × 100
Where S is the initial sample weight, B is the weight of the empty beaker, and D is the weight of the dried sample plus beaker. Report the result as percent volatile matter and reference this test method in the test report.
| 🔣 Symbol | 📝 Description |
|---|---|
| S | Initial sample weight |
| B | Weight of empty beaker |
| D | Weight of dried sample + beaker |
| % Volatile Matter | ((S+B)-D)/S × 100 |
💡 Ensure accurate weighing of the sample and beaker before and after drying for precise results. The end-point is critical; use the watch glass method to confirm.
❓ Frequently Asked Questions
🔍 What is the purpose of ASTM D5556? This test method determines the moisture and other volatile matter in fats, oils, and fatliquors used in leather softening and stuffing.
💡 What sample size is required for the test? A sample of 5 to 10 grams should be accurately weighed into a tared beaker.
⚡ How is the end-point of the test determined? The end-point is indicated by the cessation of rising steam bubbles and absence of foam. A watch glass can be used to check for condensation.
📌 What safety precautions should be considered? Avoid spattering during heating, and do not exceed 130°C to prevent overheating. Follow appropriate safety practices.